Bone Cancer

Bone cancer can be distinguished into primary bone cancer or secondary bone cancer. Primary bone cancer starts in the bone, where the cancer spreads within the cells of the bone. Secondary cancer, on the other hand, starts elsewhere in the body and spreads to the bones. Examples of primary bone cancer include steosarcoma, Ewing sarcoma, malignant fibrous histiocytoma, and chondrosarcoma.

The most common symptom of bone tumours is pain, which gradually increases over time. A person may go weeks, months, and sometimes years before seeking help; the pain increases with the growth of the tumour.

Additional symptoms may include:

• Fatigue
• Fever
• Anemia
• Unexplained bone fractures

Many patients will not experience any symptoms, except for a painless mass. Some bone tumours may weaken the structure of the bone, causing pathologic fractures.

Although bone cancer does not have a clearly defined cause, researchers have identified several factors that increase the likelihood of developing these tumours.

Osteosarcoma occurs more frequently in people who have had high-dose external radiation therapy or treatment with certain anticancer drugs; children seem to be particularly susceptible.

A small number of bone cancers are due to heredity. For example, children who have had hereditary retinoblastoma (an uncommon cancer of the eye) are at a higher risk of developing osteosarcoma, particularly if they are treated with radiation.

Additionally, people who have hereditary defects of bones and people with metal implants, which doctors sometimes use to repair fractures, are more likely to develop osteosarcoma.

The following groups of people may be at a higher risk of developing bone cancer:

• Being a child or very young adult - most cases of bone cancer occurs in children or young adults aged up to 20
• Patients who have received radiation therapy (radiotherapy)
• People with a history of Paget's disease
• People with a close relative (parent or sibling) who has/had bone cancer
• People with Li-Fraumeni syndrome - a rare genetic condition
• Babies born with an umbilical hernia

The doctor may order a blood test to rule out other possible causes for the patient's symptoms. The patient will then be referred to a bone specialist (orthopedic surgeon). The following diagnostic tests may be ordered:

• Bone scan: a liquid which contains radioactive material is injected into a vein. This material collects in the bone, especially in abnormal areas, and is detected by a scanner. The image is recorded on a special film.
• Computerized Tomography (CT): the CT scanner uses digital geometry processing to generate a 3-dimensional (3-D) image of the inside of an object. The 3-D image is made after many 2-dimensional (2-D) X-ray images are taken around a single axis of rotation - in other words, many pictures of the same area are taken from many angles and then placed together to produce a 3-D image. It is a painless procedure. CT scans are commonly used to see whether the bone cancer has spread and where it has spread to.
• Magnetic Resonance Imaging (MRI): the device uses a magnetic field and radio waves to create detailed images of the body, which in this case would be a specific bone or part of a bone. Most MRI machines look like a long tube, with a large magnet present in the circular area. When beginning the process of taking an MRI, the patient is laid down on a table. Then depending on where the MRI needs to be taken, the technician slides a coil to the specific area being imaged. The coil is the part of the machine that receives the MR signal.
• Positron emission tomography (PET): A PET scan uses radiation, or nuclear medicine imaging, to produce 3-dimensional, color images of the functional processes within the human body. The machine detects pairs of gamma rays which are emitted indirectly by a tracer (positron-emitting radionuclide) which is placed in the body on a biologically active molecule. The images are reconstructed by computer analysis.
• X-rays: This type of scan can detect damage the cancer may have caused to the bone. It may also detect new (bone) cells that have started to form around the tumour. An x-ray does not provide enough data for a definitive diagnosis, but can help the surgeon decide whether further tests are recommended.
• Bone biopsy : A sample of bone tissue is extracted and examined for cancer cells. This is the most reliable way to diagnose bone cancer. A core needle biopsy involves inserting a long, thin needle into the bone and removing a sample, while an open biopsy involves making an incision in the target bone area and surgically removing a sample of tissue.

The type of treatment for bone cancer depends on several factors, including what type of bone cancer it is, where it is located, how aggressive it is, and whether it is localized or has spread. There are three approaches to bone cancer:

• Surgery
• Radiotherapy (radiation therapy)
• Chemotherapy

Surgery - the aim is to remove the tumour, all of it if possible, and some of the bone tissue that surrounds it. If some of the cancer is left behind after surgically removing the tumour it may continue to grow and eventually spread. Limb sparing surgery, also known as limb salvage surgery means that surgical intervention occurs without having to amputate the limb. The surgeon may take some bone from another part of the body to replace lost bone (bone graft), or an artificial bone may be put in. In some cases, however, amputation of a limb may be necessary.

Radiation therapy is also known as radiotherapy, radiation oncology and XRT. Approximately 40% of patients of all types of cancer undergo some kind of radiotherapy. It involves the use of beams of high-energy X-rays or particles (radiation) to destroy cancer cells. Radiotherapy works by damaging the DNA inside the tumour cells, destroying their ability to reproduce. Radiotherapy can be used for different reasons:

• Total Cure - to cure the patient by completely destroying the tumour
• To alleviate symptoms - radiotherapy is often used to relieve pain in more advanced cancers
• Neo-adjuvant radiotherapy (before surgery) - if a tumour is large, radiotherapy can shrink it, making it easier and less harmful to then surgically remove it
• Adjuvant radiotherapy - given after surgery. The aim is to eliminate the cancer cells that remained behind
• Combination therapy (radiotherapy combined with another type of therapy) - in some cases, chemo radiation - radiotherapy combined with chemotherapy - is more effective

Chemotherapy is the use of chemicals (medication) to treat disease - more specifically, it usually refers to the destruction of cancer cells. Cytotoxic medication prevents cancer cells from dividing and growing. In general, chemotherapy has 5 possible goals:

• Total remission - to cure the patient completely. In some cases chemotherapy alone can get rid of the cancer completely
• Combination therapy - chemotherapy can help other therapies, such as radiotherapy or surgery have more effective results
• Delay/Prevent recurrence - chemotherapy, when used to prevent the return of a cancer, is most often used after a tumour is removed surgically
• Slow down cancer progression - used mainly when the cancer is in its advanced stages and a cure is unlikely. Chemotherapy can slow down the advancement of the cancer
• To relieve symptoms - also more frequently used for patients with advanced cancer